In recent years, there has been an increased focus on reducing emissions of greenhouse gases generated by burning fossil fuels. One solution for reducing greenhouse gas emissions is developing renewable sources of energy. Particularly, energy derived from the wind has proven to be an environmentally safe and reliable source of energy, which can reduce dependence on fossil fuels.
Energy in wind can be captured by a wind turbine, which is a rotating machine that converts the kinetic energy of the wind into mechanical energy, and the mechanical energy subsequently into electrical power. Common horizontal-axis wind turbines include a tower, a nacelle located at the apex of the tower, and a rotor that is supported in the nacelle by means of a shaft. The shaft couples the rotor either directly or indirectly with a rotor assembly of a generator housed inside the nacelle.
Wind turbines may include a control system or systems comprising sensors, actuators, along with hardware and software for processing sensor signals received from the sensors and generating output signals for the actuators. Exemplary sensors may include anemometers, wind vanes, rotor speed sensors, electrical power sensors, pitch angle sensors, vibration sensors, and the like. Advanced control algorithms may be implemented in the control systems to satisfy multiple objectives such as maximizing energy capture, relieving loads on structures such as blades, regulating generator speed, and the like. Control systems in a wind turbine tend to be closed loop control systems, in which a closed loop controller monitors an output value of the system, and regulate one or more input values based on the monitored output value to achieve a desired output value.